Messages in this thread | | | Date | Thu, 15 Mar 2007 13:07:36 -0700 | From | Dan Hecht <> | Subject | Re: Stolen and degraded time and schedulers |
| |
On 03/15/2007 12:53 PM, Jeremy Fitzhardinge wrote: > Dan Hecht wrote: >> Available time is defined to be (real_time - stolen_time). i.e. time >> in which the vcpu is either running or not ready to run [because it is >> halted, and nothing is pending]). > > Hm, the Xen definition of stolen time is "time VCPU spent in runnable > (vs running) or offline state". If the VCPU was blocked anyway, then > its never considered to be stolen. Offline means the VCPU was paused by > the administrator, or during suspend/resume. > >
Yes, the part in the "i.e." above is describing available time. So, it is essentially is the same definition of stolen time VMI uses:
stolen time == ready to run but not running available time == running or not ready to run
Basically, a vcpu starts off running (and this time is counted as available time). Eventually, it will either be preempted by the hypervisor and descheduled (then this time becomes stolen since the vcpu is still ready), or it will decide to halt (then the time remains accounted towards available time). Once the vcpu is halted, then eventually something happens and we should deliver a virtual interrupt to the vcpu. The time between that something happening (e.g. host I/O completing, an alarm expiring) and the vcpu actually starting to run again is accounted as stolen.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |